The invention relates to a lubrication system for a motorcycle engine, and more particularly to an apparatus for controlling the pressure differential between the crankcase and rocker box to facilitate return of oil from the rocker box to the crankcase.
The invention provides a motorcycle engine comprising a crankcase, a cam chest mounted to the crankcase, and a wall between the crankcase and cam chest. The wall defines an aperture communication between the cam chest and the crankcase. A valve assembly, which is preferably a reed valve assembly, is mounted over the aperture to selectively open and close the aperture in response to pressure differences between the crankcase and the cam chest. Air is therefore forced out of the crankcase and into the cam chest. The air is then forced into the engine""s rocker boxes through the engine""s pushrod tubes and forces oil in the rocker boxes to return to the crankcase through narrow oil drainback passages.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.